Ball joints for coupling sections of conduit together are well-known. Although this type of coupling can have a variety of different structural forms, all typically provide a certain amount of swiveling capability at a conduit joint, and all typically utilize threaded couplings to a certain extent. A common problem associated with using threaded couplings is that they can loosen because of vibration or other factors. In certain kinds of ball joints, for example, the tightening of a threaded coupling fixes a swiveling ball joint in position, and any loosening of the coupling permits undesirable swiveling, which may further result in leakage of the particular fluid communicated through the ball joint. The present invention is directed toward preventing this type of loosening.